Figure 3

Applications for the CRISPR-Cas9 system beyond gene editing. (A) CRISPR-Cas9 as a tool for inhibiting transcriptional activation. sgRNAs can be used to direct the binding of catalytically inactive Cas9 (dCas9) to the promoter regions of genes. Once bound, dCas9 can interfere with transcriptional initiation of the gene and thus inhibit gene expression. (B) CRISPR-Cas9 to promote the transcription of a gene. sgRNAs can be used to direct the binding of a catalytically inactive Cas9 protein fused to a transcriptional activation domain (dCas9/TAD) to the promoter regions of genes. Once bound, dCas9/TAD can promote transcription of the target gene. (C) CRISPR-Cas9 to image various elements of the genome. sgRNAs can be used to direct the binding of catalytically inactive Cas9 fused to enhanced green fluorescent protein (dCas9/EGFP) to various elements of the genome. This technology can be used to image different elements of a chromosome, telomeres in this example, in live cells. Dynamic chromosomal changes during growth and replication can also be imaged.